Finally swapped out my board today, I already had the Rev D board and it was replaced with a new Rev D board. and so far no 11K noise or spike in a spectrum analyzer. I also noticed a slight increase in audio output volume that i am happy about because i initially thought it was a little quiet.

So 10/10 for DSI Support for dealing with my issue so promptly and 10/10 for all the forum members who take time to troubleshoot these issues so well.

And if you boost the top end with 15dB? On my P12 boosting the treble reveals the 11kHz, like it's hidden. In normal use I can hear it faintly, but it's not visible in the spectrum analyser (below -78 dB).

Just mailed to support@davesmithinstruments.com to let them know I also have that annoying fizzy aliasing like artifact in the back ground in almost every patch.
My P12K runs on 1.2.0 now but had it from 1.0.1 and heard it almost instantly.
Hope they come up with a solution soon.

Augustyniak wrote:Hi Benny here,
Just mailed to support@davesmithinstruments.com to let them know I also have that annoying fizzy aliasing like artifact in the back ground in almost every patch.
My P12K runs on 1.2.0 now but had it from 1.0.1 and heard it almost instantly.
Hope they come up with a solution soon.

Augustyniak wrote:Hi Benny here,
Just mailed to support@davesmithinstruments.com to let them know I also have that annoying fizzy aliasing like artifact in the back ground in almost every patch.
My P12K runs on 1.2.0 now but had it from 1.0.1 and heard it almost instantly.
Hope they come up with a solution soon.

Actually my bad here, if you have 1.2 you're on the most current. Talk to support, they'll help you out

Augustyniak wrote:

Pym wrote:Try updating to the new beta OS first and see if it helps

Augustyniak wrote:Hi Benny here,
Just mailed to support@davesmithinstruments.com to let them know I also have that annoying fizzy aliasing like artifact in the back ground in almost every patch.
My P12K runs on 1.2.0 now but had it from 1.0.1 and heard it almost instantly.
Hope they come up with a solution soon.

Is the 1.2.0 on davesmithinstruments.com the same as the one on the forum?

Thanks already mailed support.

Not sure if this will help or not, but here is what I found upon investigating the aliasing and fizzy sounds from the prophet 12 over time. For me this only occurred when listening to the output through the headphone jack. When I would plug into my mixer, I did not hear these anomalies either with headphones or through speakers. Of course, the mixer is connected to the left and right outputs of the synth. I became convinced there had to be an issue with my headphone jack. For reference I was using a pair of sennheiser 280 had headphones.

Well, recently I purchased a pair of brand new akg m50x headphones. Like the sennhiesers they exhibited the same behavior when listening through the headphone jack. But, these headphones were part of a package on amazon that included a small FiiO headphone amplifier. Just for shits and giggles, I decided to plug the headphones into that small amplifier and then into the synth. Lo and behold, there was no more aliasing and fizziness! Same thing when using the senheiser headphones. I am convinced that there may be an impedance or output mismatch with some headphones straight into the headphone jack. Hence why I didn't hear the issues with headphones plugged into my mixer. The headphone amp in the mixer boosts the signal and provides more power to the headphones. Maybe there is not enough output power to headphones straight form the jack? Honestly, I can't explain what the mismatch might be. It is above my pay grade. Maybe Carson or Chis can. What I can tell you is if your scenario matches my above scenario there is an easy fix. I'm happy that it is not something i hear from any output now.

Is the 1.2.0 on davesmithinstruments.com the same as the one on the forum?

Thanks already mailed support.

Not sure if this will help or not, but here is what I found upon investigating the aliasing and fizzy sounds from the prophet 12 over time. For me this only occurred when listening to the output through the headphone jack. When I would plug into my mixer, I did not hear these anomalies either with headphones or through speakers. Of course, the mixer is connected to the left and right outputs of the synth. I became convinced there had to be an issue with my headphone jack. For reference I was using a pair of sennheiser 280 had headphones.

Well, recently I purchased a pair of brand new akg m50x headphones. Like the sennhiesers they exhibited the same behavior when listening through the headphone jack. But, these headphones were part of a package on amazon that included a small FiiO headphone amplifier. Just for shits and giggles, I decided to plug the headphones into that small amplifier and then into the synth. Lo and behold, there was no more aliasing and fizziness! Same thing when using the senheiser headphones. I am convinced that there may be an impedance or output mismatch with some headphones straight into the headphone jack. Hence why I didn't hear the issues with headphones plugged into my mixer. The headphone amp in the mixer boosts the signal and provides more power to the headphones. Maybe there is not enough output power to headphones straight form the jack? Honestly, I can't explain what the mismatch might be. It is above my pay grade. Maybe Carson or Chis can. What I can tell you is if your scenario matches my above scenario there is an easy fix. I'm happy that it is not something i hear from any output now.

Hope this helps.

Mark

Hi Mark,

Thanks for the ideas but tried almost everything, it is sill there at the phones (Sennheiser HD 580) out and the main out even with no midi or usb connected.
I am in contact with their support and will mail them a audio file so they can hear it too.
Greetings Benny.

(wrote a longer description here but the forum timed out so I lost the whole post - why is there a timeout on a post reply window??)

I just doesn't sound great. The factory patches are mostly awful, but it is also very hard to make something that sounds nice. If the factory cannot even make great patches, can the average user?

Probably the main reasons are as I see it - or hear it:

Too much digital noise. Either aliasing, digital controller noise or faulty signal processing. It is at low dB levels - around -85 dB but it is semi-broadband and when you add 12 voices it increases with > 12 dB. Have tried three different PCB's and none of them had great sound - although the C rev was less noisy than the two D revs I tried (where one of them was quite bad). I had good help from DSI support - fast and quick response - so they do a great job.

Basic waveforms are not "correct. Sines are not sines (a single frequency) but sounds more like bells, saws are not saws, pulses etc. And that makes everything sound to harsh. Whether it is the analog pathway or digital source that is not good is not clear to me, but most other synths I've used, do not have that problem.

So instead I bought a used Tetra - and THAT is a great sounding synth. Considering to add more to create an 8, 12 or 16 voice analog synth.

If you really need all the possibilities in modulation and combination of oscillators as you have in the P12, you are probably much better off with a VST synth and a MIDI keyboard at a much lower price. The P12 does not sound like an analog synth, and I think my Korg Radias is a much better synth.

The DSI tech thinks the noise issue is on my end. That may be true. I could be getting distortion due to resonance/vibration even in my headphones

I had trouble reproducing what I was hearing, so I will stop worrying about it

Someone above said sine waves aren't much like sine waves. Mine look exactly like sine waves in the output file. If there's distortion, I am not seeing it. I don't have a good spectrum analysis program though. The saw waves don't look very saw wave like to me. But it sounds like sawtooth wave, so not worried about it.

michaeljhuman wrote:Someone above said sine waves aren't much like sine waves. Mine look exactly like sine waves in the output file. If there's distortion, I am not seeing it. I don't have a good spectrum analysis program though. The saw waves don't look very saw wave like to me. But it sounds like sawtooth wave, so not worried about it.

I've examined the sinewaves on my P12, and they look and sound fine, with under 0.7% distortion (and that was mostly benign 2nd harmonic i.e.one octave above the fundamental).

I'm a relatively new P12 user, but I noticed this same 11k sound recently and contacted DSI about it, they sent me a new board straight away and I just put it in. The 11K sound is gone, so this is a fix. However, I've now noticed there's a permanent high pitched sound in the background, fainter than the 11K sound. If anyone else has heard this, I have found a fix for it which seems to also help with background white noise:

If you stack A+B, then edit layer B and turn its volume all the way down, the noise disappears. This is the same the other way round, i.e. you can turn the volume on layer A all the way down and just listen to layer B and it's the same, but you have to stack them. For some reason this stops the noise. You can only really notice the high pitched noise on very filtered bass sounds, which tend to be really quiet. Obviously this fix means you can't use layering, but I think it's rare that you'd layer A+B for a bass sound. Regular sounds are loud enough that you don't hear it.

Another thing is watch out for what impedance input you're using to listen to/record the prophet. I've been using some DI inputs on a preamp of mine which are really high, and I've been getting lots of "aliasing" static-y noise all the time. Really loud on bass sounds. I tried some different inputs, and found that if you put it straight into a line input with regular impedance there's almost no static-y noise. Others might already know this but I didn't! If using DI box then set it to line not instrument! For some reason before I presumed it would need instrument-type impedance. (Lack of experience with keyboards!) The impedance values are not specified anywhere in the manual.